This invention relates to a porous silicon nitride based article of high strength and low mass. It also relates to a porous silicon nitride based article of high strength and low mass which is impregnated with a lubricating material to make it self lubricating.
In applications such as rotating or oscillating shafts and bearings, high strength, low mass materials are important.
Self lubricating articles are used in various applications. For example cemented carbide shafts are used because of their high wear resistance. These articles have to be lubricated which is relatively expensive. They cannot be made self lubricating. Steel or bronze shafts which are oil impregnated are unsatisfactory because of unacceptably high wear on the shaft even though starting torque is low due to the oil. Self lubricating articles having high strength and low weight are desirable in various applications such as in shafts which can be used in place of bearings and sliding membranes.